Thank you for your contribution! I can confirm that the mat changes its colour, usually within 3 months. Are you really sure that the higher nitrate consume in plant-tanks is only due to the "hamburger"? Isn't it the general higher turnover rate in plant physiology in these tanks with -usually- extra high lightning doses and plenty of CO2? I dont believe that a "hamburger" that runs within the limits (given by O.Deters et al. of 5- 10 cm /min provides anaerobic conditions within the mat. trace elements: are they really >consumed<, or are they just bound by the "mud [german "schlamm)within the mat. So after a while, the mud would be saturated and give back its load of trace elements to the water. This mud works as a light cation exchanger. If you can read german, you can check out "the" forum for the Mattenfilter,http://www.aquaristikimdetail.de/
where these question have been discussed quite often and detailed. If you could add your experiences there (also in english), it would be highly appreciated! So there's again a lot to learn from the dutch guys!

Jorg,
I am sold on the concept, but I have a couple of questions:
1) What is the maintainence required on the filter pad itself, ie other than cleaning its outside every week, what about replacing the pad, whats the frequency on that?
2) Have you noticed any spikes in Nitrate, Ammonia or phosphates? What will be the break-in period ie time till the filter pad is biologic ally and functionally stabilized?
3) Do you think it is best to place the powerhead as high as possible to get most flow across the filter pad? Is it an issue, or can the powerhead be placed anywhere along the length?

Ich ignoriere jetzt mal die Fehler und Du bitte die meinen
1 Maintenance: That depends a little bit on the structure of the mat, if you choose a fine mat with little pores all sand, mud etc. will easier stay on the outside. But these fine mats take longer till they are settled by bacteria.In my AQ I occasionally pull off some layers of cyanobacteria (bluegreen"algae") that live on the first 10cm below the water surface. That's it. No pulling out. Replacing the pad: there are aquarists who used their mat in different aquariums for more than 10 years, but if you have some fish like loricariidae which graze on wood and also on the mat, this might be reduced drastically. If you want to avoid that, you can opt for an "outside HMF" where the mat is placed in a separate filter aquarium below the display tank.

2 Cycling the tank: when i started with my AQ and the HMF (before i was using Eheim canister filters) i didn't measure NH4 or phosphates. There is a good (german lang.)article about cycling a tank with a HMF (especially about the different stages of microbial activities) that i will link here ASAP.
Generally speaking, you cannot predict when the filter(reactor) will be biologicaly active. The same laws of nature apply to all our aq activities, so there is no difference in starting an AQ with or without a HMF. Wait at least 2 - 3 weeks, start feeding fishfood, measure NO2 and when the spike has occured, add fish. How fast that nitrite pike will appear depends on several factors, like plant consumption on NH4, NO3,temp.,lighting, pH......You can fasten that process if you add some filter "mud" (the brown material inside the mat that can be squeezed out and which is full of bacteria) and kind of innocculate the new mat. I recently started with a new AQ and used a mat from an other AQ, there was no NO2 change at all (zero).
3.) the flow of water across the mat is constant for the entire area, that sounds weird, but can be proven easily:

the inlet of the pump can be placed anywhere, but i would recommend it not to get too close to the bottom, so that the "mud" from the filter can remain on the ground and work as an additional filtration area.

Hoi Jorg,
Vielen danke fuer Ihre antwert. All my german is self learnt, the result of working with german colleagues and having an advisor who spent many years in Graz. I just ask them to teach me specific words, the grammar is easy as it is similar to most Indo-European languages.
I will start working on the setup this weekend and I hope to have your help for it. One last thing I wanted to know was, in the pictures, the filter pad was installed before putting the substrate in, so is it true that once the substrate goes in there is none on the filter side, or do we bury a small part of the filter pad in the substrate.

If you want to be absolutely on the safe side you can dig in the filter pad on both sides. Some aquarists even place(=silicone) a small, bentcircle of plexiglass on the bottom of the tank around the lower side of the mat, so to prevent the substrate from gliding into the filter area once the pad should ever be taken out of the tank. Will you build a cornered HMF or the standard version ?

The Hamburger Mattenfilter has gained it's rightful place among aquarists. Even mail-order shops offer the mat now, even though they would prefer to sell more expensive filter constructions. Since 1996, the mattenfilter has been
explained on these pages in text, drawings and pictures.
In the course of time some questions arose on behalf of readers and users and I get emails nearly everyday about this. The answers to questions have been incorporated either into the text or into these FAQs.

Can the Filtermat be too large ?

No, but the velocity of flow might get too low. If it is too low further problems arise. On one side suction is
reduced. By this, a part of the biology supposed to take place in the filter shifts to the aquarium. In my
experiments, some considerable nitrite levels appeared if speed was reduced too much.

I read that there should be a gap of about 2cm between mat and pane, but then the pump doesn't fit in between any longer. Can I have more distance or does this change anything in the filtration effectiveness of the HMF?
No this has no effect at all on filterpower. The 2cm result because of the construction and are thought as a help in
understanding.

Can the matfilter be used in seawater aquaria ?

Usually not. According to its principle the matfilter produces nitrate and this is disposed of by water changes or plant growth. In a seawater aquarium the water changes are negligibly small so that this means there is no way of nitrate disposal. Algae as well do not absorb nitrates too much. So the aquarium has to get along with all the nitrate. In a seawater aquarium one therefore installs skimmers which extract proteins etc, before turning into nitrate.

How high is the waterspeed in the mat really ?

Very much higher than in the calculation results. The calculation does not take into consideration the narrowing of the diameter of the mat and its getting choked up with mud. Therefore the real speed is much higher. In practice the recommended approximate values turned out to be good as they contain some safety reserves. For this reason there is no danger if one calculates a too low speed of waterflow.

The calculation does not prove right

An aquarium is a biological system and no exact technical construction. Accordingly, it can be adjusted rather
inaccurately. The recommended values concerning Speed of waterflow and circulations per hour are
approximative values, which resulted mostly from experience. If the speed of water flow is only 2cm /minute but the flow rate in the tank per hour is alright no problems are to be expected. The flow rate could also go down to 1x per hour or rise to the threefold. It will have no effect, if the speed of the wate rflow remains within limits. Basically, my calculations only show the lower limit of dimensioning, the filter can very well be larger .

Can I take a mat from Home Depot/Bauhaus ?

There a positive and negative experiences alike. I supect that Home Depot/Bauhaus/Obi/... doesn't get supplied
for by always the same plastics producer but changes its range of product over time and has regional differences. For this reason one cannot make any general statements.. Its safer to use real filtermats. You can find them here.

How high must be the difference in water height in front of and behind the mat ?

In new mats one often finds no difference in waterheights. This does no matter. To exclude any unwanted
circulations one can, in example, check with a suspension of dry food if the water goes through the mat or if there
are some leaky parts at the margins of the mat. Maximum height difference is somewhere around 4 - 5 cm, in my
experience. Above that, the one-sided water pressure is so high that the mat bows heavily and does not fit tight to
front and backsidewalls. Then one should clean the mat more intensively, Note: There are aquaria where this never occurs.

Where is the area of calculation being measured, from upper edge to ground or to the bottom side

Correctly from upper edge to ground, but this is no exact science. One gets along well if one takes the lenght of the sidewalls. As mentioned above, the existence of the Mattenfilter is more important. It cannot be too large, but I would not size it smaller than at the levels mentionned.

Where to buy the mat ?

I bought my foamed plasticmats at specialised dealers. There one can let it have cut, aswell. Meanwhile all
specialised mail order shops feature the mat.

How thick should the mat be ?

A mat thickness of 5 cm turned out to be okay. Certainly, one can choose a thicker one, but stability does not
increase linearly. One says that the main activity happens in the first centimeters. The other centimeters are for stability.

Can I do without a pump ?

Two of my tanks have a Mat on the entire backside, made of a 2cm coarse foam mat, which has been glued with
aquarium silicone onto an extra pane of glass. The Pump sucks water at one side and pushes it from the other side
through the tank. A river aquarium for catfishes. In the mat enough organisms pile up and streaming is sufficient.
But the aquarium is oblong. I would not recommend that for standard aquaria.

How long does a Mattenfilter needs to get going ?

Oh, difficult to say, Expect four weeks, rather more. It depends decisively on water contamination. It really works well from week 12 on, or more. But then it also works for a lifetime. If the tank has been operated before with a canister filter one could and should let it run parallely for a time (ca. 2 -4 weeks). Negative results are not to be expected.

One says that it should still be squeezed out.

No. It is not in the nature of a mattenfilter to need any care. Only some occasional sucking off every few
waterchanges is necessary. In tanks that are extremely contaminated this might be the case more often and
more periodically. Oddly enough, it also happens in normal aquaria. But one does not need to and should not
squeeze it or de-mud it by principle.

Can a mattenfilter be operated externally, too ?

Principally yes, but some major advantages get lost: An internal mattenfilter develops no suction effect worth to
speak of, as the suction takes place over a large area. Therefore, a Mattenfilter "eats" no food or young fish. Now
if one uses the suction pipe of the filter to bring water to the filter then again the suction basket might get blocked up with plant parts. I do not believe this is a good idea.

"I has happened twice that a part of the water finally made it to the appartment. The reason was, besides me, the
hoses or the canisterfilter. Beside others, the BIG advantage at the mattenfilter is that it is within the tank. If one
uses the Mattenfilter externally, one also looses this advantage." (Henry Hoch, October 1999)

Can one also use two mats ?

Of course, if the aquarium is 1.80 m or more then I would recommend that, if one takes care that there are no larger parts without circulation. The circle effect gets lost hereby (applies to canisterfilters, too). If in these tanks one installs a filter on one side only then, possibly, the last 80cm are not moved any longer. One can prevent this if one places the gushing out pipe to the other side and thereby pushes the water towards the mat.

Which filter foam is better, the fine or the coarse one ?

Doesn't matter, I prefer the fine foam. It also does not get sealed. But if one has some fish which mess in the mud
or eat a lot, e.g. large cichlids, then the coarse one will serve better. The foam is nothing but the "stock shelf" for
the mud, the supporting framework. If that is now fine or coarse does not matter for the filtration. Only the circeling might take longer in a coarse mat, as its riddle effect is not as high.

How old does a mat get ?

My oldest mat lived to be eleven. The mats I had to change had been beaten up with pushes from the hose at
multiple cleanings. No wonder, it were breeding tanks with a lot of Baby brine shrimp feeding. But even under
these conditions, they are in it for 3 - 4 years for sure and without any intensive cleaning.

How large has the mat to be cut ?

In the width it should be 5 mm broader than the inside width of the tank. Height should be chosen so that it is 10
mm higher than the waterlevel. Apart from that , the size results from the calculation

Must the mat go down to the glassbottom ?

Yes, that's recommended. Otherwise there might be a small gap between mat and substrate, where the water
might pass through unfiltered.

What about the mud behind the mat ?

One can leave that mud behind the mat. Usually it does not distract there and it serves, in some sense, as a
store for bacteria and buffer.

Does one safe waterchanges with a Hamburger Mattenfilter ?

No, the mattenfilter does not replace a waterchange. A real waterchange has still to be done.

So what's the point with the HMF ?

It makes a substantially very stable biological environment in the aquarium. This is due to its true and large mass
of filtermud. In canisterfilters there is less and in addition, the aquarium (plants, substrate..) filters itself. In a
MF-aquarium, one can quite possibly suck off the substrate or do some large scale water changes. The MF will
buffer that. The MF-aquaria are far more resistant against influences from outside. They are biologically stable.

Canisterfilters do work, why then a Mattenfilter ?

No one says that aquaria with canisterfilters have to be adapted at once. But for a new installation one should
think about a filterchange. Usually, aquaria with a canisterfilter do work as a large part of the filterwork takes
place in the aquarium and not in the canister. Experiments showed that in average canisterfiltered aquaria, one
could remove the filter wool and nothing changed in the aquarium. That means that the filter does not help much,
it only provides watercirculation.

Does it make sense to use a circulation pump filter as a pump for a internal MF ?

Principally yes. But one should bear in mind that, because of frictional resistance inside, the net pump power
cannot be compared any longer to the given pump power. It is reduced. This should be checked when doing the
mathematical dimensioning.
For a repetition: One assumes a twofold circulation of the tank per hour. That means that the pump power per hour must be twice as high as the tank volume (with or without substrate, does not matter). Thereby the waterflow in the mat should be between 5 - 10 cm /minute. If the Eheim pump shows 620 ltr /h and the tank has a volume of 300 ltr/h then it might get rather on the short side of 2x per hour. This is because the real pump power is only 50 â€“ 75 % due to the filling material and its density in the canister.

Are iron fluctuations in the mat preventable or dangerous ?

No, completely normal. The iron which comes from fertilizers into the tank is held stable by chelators. These
chelators do not work forever, the the iron precipitates and gets into the substrate or into the filter. However, some traces come back from there, so that a certain iron supply from the filtermud is given.

Mattenfilter and mould film

A mould film consists of bacteria living on the surface. They are of no importance in small numbers. So if a
mould film appears, that is no reason for panic. A mould film has nothing to do with filtration, both are principally independent matters. A mould film behind the mat is absolutely not critical. I would not do anything against it. At the aquarium side, a mould film can be prevented or fought against by a handy placement of the pump outlet pipe. Otherwise the usual operations: periodical removement with blotting paper or a litre mug.

Mattenfilter and sand as substrate

Of course, wheter gravel, sand or no substrate at all like in breeding tanks, a mattenfilter will always work. This is one of the essential points of a MF. It alone shall, must and will be sufficient to hold all the microbiology for the aquarium. That's the job of a Mattenfilter.
--------------------------------------------------------------------------------

Ach so! Ich lerne neu things everyday! Isnt Servus latin for comrade? Also, I thought servus was good bye in german, but I have since learned its only in some regions like Bavaria, is das richtig? Got your PM and I will reply back with the answers in a few hours.

Here is my Mattenfilter in a 10g tank. I tried to keep the setup as cheap as possible, therefore I didnt want to pay the $15-20 for the cable channels (cablemate) at HD. I instead simply glued sections of the filter material onto the glass (the 10g tank was free, and if these things indeed last several years, then might as well make it semi permanent). I wasnt able to find a single piece of mat large enough for under 7 bucks, therefore I bought a rectangular block which I then cut into 1" thich pieces, the bottom most section is 1&3/8". I came up with the area according to the calculations given in http://www.janrigter.nl/mattenfilter/. If I understand correctly, there are two unknowns in that equation, the Area of the filter and the flow rate, which depends on the area some way. Therefore, I set the flow rate at 10 and then got the area - 396.66cm2. The height of the tank was 26.25 cm same as the filter pad height and the width was then 15cm. However, the calculations are inexact and IMHO dont matter too much, the reason being, to calculate the flow rate we will need the surface area, which depend on the pore size and the thickness of the pad, not just the 2D length and width. Therefore, I think my filter design isnt optimum and the throughput is going to be more than the desired value. Moreover, my powerhead moves 4 times the tank volume per hour, 2 times more than the desired value. But I spent $16 for the whole thing and I am sure it must work somewhat.

Is there anybody who tried the Mattenfilter concept and who can report about his or her experiences ?
-Jörg

I have used this in my most sucessful tanks since the early 70's. There was a woman who wrote about this and also specially designed undergravel filter variations for marine tanks and hybrids between the two filters in articles in the 60's that I was able to read from the local fish club's back "exchange magazines". Some of those articles contained the seeds of the idea of a sponge filter. I believe her club was called the Salt Water Aquarium Society of Hawaii, and the club pub was called Swash! I also talked to aquarists at the public aquarium where I had volunteered, and was told that they had used the mattenfilter or a variation even earlier, when the aquarium opened in the early 50's, and still used a modification of it where it was in a separate tank attached to the system so any maintenance would not "spook" the fish. It is not a far stretch to compare many pond filters with vertical filter pads to a mattenfilter. They are just remotely located away from light and fish to avoid being clogged with algae or debris.

The objections to the appearance of the filter as a background has changed with the introduction of Java moss, Java fern, and other plants that attach without needing their roots in a substrate. Java moss also prevents the substrate clogging. Some big stitches made on the surface of the mat with monofilament fishing line makes it easy to "plant" an instant wall of Java fern and java moss. You can also cut some random shaped holes in the mat, then patch them with larger pieces, to increase surface area while keeping thickness constant and creating a plant ledge on top of each patch.

I've found the mattenfilter is a real boon in freshwater tanks and I was breeding lots of fish in those tanks. I always seemed to win every local fish club's Growth Contests, and was often the first to breed a new fish, especially the African and Central American cichlids. A few years ago I decided to try the new hi tech filters and they have been much more prone to breakdowns and high maintenance. Plus I have not had the same success with fish breeding or even with plants as in the Mattenfilter tanks. I'm looking forward to switching my tanks back to the mattenfilter as I get the chance.